As hybrid electric vehicle (HEV) and electric vehicle (EV) technology may be adapted to support full and partial electric drive operations in any number of vehicles, such as but not limited to HEV and EV technology in automobiles having internal combustion engines. These technologies may include advantageous electrical capabilities, such as but not limited to regenerative braking, automatic engine stop/start operation, and the like. These electrical capabilities, however, tend to introduce voltage variations in the electrical system, which are different from non-electrically driven/assisted vehicles. This present problems different from those typically found in a constant voltage vehicle systems, like internal combustion automobiles.
FIG. 1 illustrate a graph 10 of electrical variations commonly associated with HEV and EV technology and its result on battery voltage. The graph generally illustrates electrical variations influencing capabilities of a vehicle battery to provide a constants 12.8V. One variation may result from battery discharge during acceleration, another variation may result from battery charging during deceleration (regeneration), another variation may result from automatic engine shut-down after vehicle stop, another variation may result from battery discharge during a vehicle stop phase, another variation may result from hot engine restart or engine start/stop during engine standstill, and yet another variation may results from controlled battery charging.
These and other voltage variations can be problematic and disruptive to vehicle systems and other vehicle loads subjected to the same, such as but not limited to voltage sensitive loads, like instrument panels, entertainment systems, lighting systems, etc. To facilitate customer acceptance of the HEV and EV technologies, it may be desirable to avoid or limit noticeable performance variations in voltage sensitive loads.